Short Description - Kaiser Bolted Bracket:
The Kaiser Bolted Bracket is a special moment frame for steel construction. It is a
simple, but unique approach because it consists of a steel haunch casting which is
installed through bolting. In the retrofit version, the part is drilled and bolted in place
without any welding. In the new construction version, a heavy fillet weld is done in the
shop and then the beam is fully bolted in the field.
Lab reports and certifications:
The Bolted Bracket has been extensively tested and the full lab reports are available on
request. It has been installed in 29 buildings to date including three LAX airport
terminals, hospitals in Los Angelas and projects in Washington, Oregon and Utah. The
Kaiser Bolted Bracket is just completing the process of becoming pre-qualified per
ANSI/AISC 358-05 for the AISC Seismic Provisions.
Design Specifications:
Size calculations for retrofits will require an engineer to review the existing beam /
column connection. In both versions, the connection stiffness remains unchanged from a
pre-Northridge connection, making the calculation process very simple.
In new construction, the AISC latest seismic provisions guidelines should be followed
and when properly applied, continuity and doubler plates can be eliminated. This can lead
to considerable savings.
When these guidelines for seismic applications using a strong column, weak beam
environment are followed, the quick-chart of beam sizes can serve as a guide. There
are only a few bracket casting sizes and each bracket covers a range of beams. Follow the
ANSI/AISC 358-05 Prequalification guidelines and our spreadsheet for detailed size calculations.
Design Fees:
The Kaiser Bolted Bracket is a pre-engineered steel casting hardware approach to
moment frame installation. It does require designing to a strong column / weak beam
condition which is not unique to the Bracket, but a common standard requirement. For
this reason there is no special engineering involved and the EOR can do the calculations.
We do provide technical support as needed and check that the criteria have been satisfied
for the installation. Although the bracket is patented, we charge simply for the part
purchase and do not charge any engineering or license fees.
Savings Advantages:
Retrofits are drilled and bolted in place and require no welding.
New construction installations need a heavy shop fillet weld, no doubler plates or
continuity plates and require smaller beam sizes than the RBS connection. Erection
involves bolting the beam in place through shear tabs and then proceeding with other
operations such as deck installation concurrently with installing the bolts in the Bracket.
Initial frame construction is greatly accelerated through this approach. Slotted and
tapered holes make bolt fit-up simple and eliminate alignment problems.
Cost Information (New Construction):
Each bracket kit includes one casting and the bolts required for the size. These are
normally A490 1-3/8” or 1-1/2” Bolts. The price list on the CD or printouts may change
slightly as supply costs change, but these should be minor and can be confirmed as
needed. A typical connection requires a bracket set for each of the top and bottom
connections. Castings are FOB Seattle with the bolts FOB Saint Louis.
The information on our recent cost study, along with all of the details on installation
should be helpful in doing your own cost analysis for weld and installation calculations.
We typically find that the installed cost runs around 30% under the RBS connection
without including the additional time savings for the erection schedule. In addition,
the process is so simple, that it does not require any significant design or procedural
training.
William Gibb
bill@steelcastconnections.com
(206) 250-7035
Steel Moment Connnection Cost Comparisons
Location:
Building Size:
Floor Plate:
Stories:
# Connections:
Typical Steel Beam
Typical Steel Column
Typical Beam Span
Typical Flr-to-Flr
Material Costs1,2:
Erection Costs1,3:
Field Welded Connections1,13:
Weld Special Inspection14:
Los Angeles, CA
280,000
18,667
15
342
W27x84
W14x233
24
15
$2,338
$908
$300
$80
ft2
ft2
ft.
ft.
per ton
per ton
per ton
per ton
Bolted
BracketTM
Reduced
Beam Section,
RBS
Side Plate
Sure FrameTM
SSDA Slotted
WebTM
Material Costs1,2:
Beam4
Column5
Side Plates6
Kaiser Brackets7
RBS Cutout8
Beam Slots9
Total Material Costs
$2,357
$4,086
$0
$1,256
$0
$0
$7,699
$2,592
$4,086
$0
$0
$400
$0
$7,078
$2,121
$3,677
$1,298
$0
$0
$0
$7,096
$2,357
$4,086
$0
$0
$0
$280
$6,722
Installation Costs1,3:
Beam4
Column5
Field Welds10,13
Weld Special Inspection10,14
Total Installation Costs
$915
$1,587
$0
$0
$2,502
$1,007
$1,587
$857
$229
$3,679
$824
$1,428
$744
$198
$3,194
$915
$1,587
$827
$220
$3,549
Cost/Connection:
Proprietary Licensing Fee11
$10,201
$0
$10,757
$0
$10,290
$168,000
$10,271
$40,000
$556
$189,975
$581
$198,418
$277
$68,145
Item
Bracket Savings/Connection12
Total Savings
1
Source: RS Means, Building Construction Cost Data, 63rd Annual Ed., Reed
Construction Data, 2005
2
Materials include: steel base price, extras and delivery to ship, drafting, shop fabrication
& warehouse retarding, shop coat paint, trucking to job site
3
Installation includes: Unload and shake out, erect and plumb, field bolt, crane & minor erection
equipment
4
RBS beam cost is 10% higher to account for stiffness loss at the weakened sections; Side
Plate beam cost is 10% lower to account for side plate effect of increased beam stiffness
5
Side Plate column cost is 10% lower to account for deeper column sections
6
Side Plates weight: 1.2 psf per SidePlate.com web site
7
Kaiser Bracket costs includes (4) N2.0 brackets, shop welding
8
RBS includes (4) flange radius cuts per beam, and weld access holes; Source: Camron
9
SSDA slotted web includes (4) web cuts, and weld access holes
10
Full penetration welding and ultra-sonic testing included
11
Source: SSDA web site (www.ssda.net); Side Plate System ($.60/s.f. licencising fee)
12
Kaiser Bracket reduces erection time by up to two times than that of other connection types,
allowing a compressed construction schedule and reduced interest paid on construction loans.
Unfortunately, interest savings cannot be reflected on this table
13
Source: The Erection Company (10 hours per beam at $80/manhour plus $16.5/hour
weld
machine, wire, etc.)
14
Source: Construction Testing & Engineering, CTE (3 hrs per beam at $80/manhour plus $15/hour
testing machine, etc.)